Replace leading ellipsis when sanitising output file/directory names

Avoids creation of invisible files/directories on Linux/OSX for programmes
like "…Sings the Beatles"
Use --rtmpdump in preference to --flvstreamer

Internal references to flvstreamer changed to rtmpdump and --rtmpdump
is now preferred option to specify location of binary.  --flvstreamer
is retained as synonym for --rtmpdump and flvstreamer options is still
supported in options files.
Restore lines accidentally commented out